High quality audio and video systems comprise individual component elements. Components such as tuners, receivers, media players, etc. originate audio or video signals. These signals are conducted to at least one amplifier or other processing component by cables. In the case of audio, the signals often have relatively low power and often are analog, i.e. have the audio content encoded in the amplitudes and phasing of the waveform.
In most cases each cable comprises at least one internal signal conductor and an outside shield that forms a second conductor. The cables terminate with one of a variety of different plugs or jacks that mate with connectors forming a part of the component involved. Such cables have been available of course, ever since recordings have existed whose sound content has been reproduced using electronic amplification. (Hereafter, “plug” will refer to the connecting element on the cable. “Socket” will refer to the connecting element usually present on the audio component housing.)
A variety of designs exists for connector plugs and jacks. Perhaps the most common is the RCA system, which has on a surface of the plug or jack, a central pin or prong to fit into a central hole on a corresponding socket. An annular ring projects from the surface and surrounds the pin of the plug. Pushing the plug into a corresponding socket, electrically connects the ring to the outer surface of a projecting socket ring. Other terminal systems have other arrangements.
Flat 75 Ω cable has been used has been used for many decades for RF conduction such as from a TV antenna to a TV set. 75 Ω cable has a pair of conventional copper wires embedded in a flat plastic strip that insulates the individual wires and holds them in a prescribed spacing.